Apple said that it will require developers to support the iPhone XS Max and 12.9-inch 3rd-generation iPad Pro (if available on iPad) for all new apps and updates starting March 27.
Apple originally stated that app developers will need to support iOS 12 from March at the end of 2018. Today’s developer news statement serves as a reminder but also clarifies the details. The iOS 12.1 SDK had not been released when Apple first set out the deadline. The 3rd-generation iPad Pro was also announced in the interim and is now part of the requirements.
Apple will require all app submissions to supports its latest devices, plus screenshots for App Store listing. Note that making the iOS 12.1 SDK mandatory does not mean app developers have to cut off older operating system versions, although >80% of devices are already running iOS 12 so many will choose to do that of their own accord.
In the same vein, watchOS apps must be built with the watchOS 5.1 SDK and ensure they support the new screen sizes of Apple Watch Series 4.
Apple also invited developers to contact them if they need to request a special exception to circumvent more stringent memory management policies introduced in iOS 12 and tvOS 12.
Apple is expected to release iOS 12.2, watchOS 5.2, macOS 10.14.5 and tvOS 12.2 on Monday. Developers that use Swift will want to adopt the iOS 12.2 SDK as soon as possible, as it includes Swift 5 and ABI stability. This enables apps that include Swift code to be smaller in file size, and launch faster, as Apple will be bundling the Swift frameworks in the operating system for the first time.
Source: 9to5mac